Ischemic heart disease in blacks is characterized by microvascular dysfunction, left ventricular hypertrophy, increased sensitivity to cathecholamines, a predominance of salt sentivity, hypertension, and relatively worse outcome for the extent of macrovascular disease. There is evidence to support the hypothesis that a loss of nitric oxide action plays a pathophysiologic role in this vascular diathesis. The project will compare nitric oxide-dependent vasomotor function in black and white subjects using a non-invasive, brachial ultrasound technique. Measures of nitric oxide release (flow-mediated dilation and platelet cGMP) will be examined in 300 subjects with and without hypertension. These findings will be compared and also related to echocardiographic measures of left ventricular hypertrophy to investigate the relationship between vascular and myocardial effects of nitric oxide insufficiency. These subjects will be studied on an outpatient basis both in the CRC and at Boston Medical Center over a 5 year period.